Intelligent Network (IN) services is a generic term used to refer to any services in a telephone switch other than routing the call to a fixed physical location based upon the telephone number dialed. For example, a telephone switch could be programmed such that calls are forwarded to a different telephone number at particular times of the day, or such that multiple incoming calls to the same telephone number are each routed to different telephones. The switch could be programmed to bill the called party rather than the calling party (800 service), or to bill at a different rate (900 service). These and other variations of IN services are available currently.
One example of IN services can be appreciated by considering a large hotel chain which provides a nationwide, toll free number for customers desiring reservations. The hotel chain may have offices around the country, and each office may only be staffed at certain selected times or days. Further, busy hours at one office may occur simultaneously with relatively idle hours at another office, requiring that calls be rerouted depending upon the time of day. Nonetheless, it is desirable that all customers have one telephone number for all reservations, regardless of where the customer is located, what time of day it is, or which day of the week it is. Techniques to allow such a service are in existence currently, and are normally referred to as intelligent network (IN) services.
FIG. 1 shows a high level block diagram of an IN system including an exemplary corporate office 104, six telephones 105-110, two exemplary telephone switches 102-103, a local router 113, which may be a Private Branch Exchange (PBX) of the type well known in the art, and a service control processor (SCP) 101. Each of the telephones 105-110 would be manned by a service representative, and the particular one of telephones 105-110 that the call is routed to is substantially immaterial once the call is routed to the proper corporate office.
Considering the hotel chain example, each switch includes a set of software programs which recognize that an incoming call is the result of an 800 number being dialed, and send an appropriate query to SCP 101 via the appropriate one of communication links 111-112. SCP 101 is a computer based system which stores information relating to the customer's routing requirements and sends messages in response to each query to switches 102-103 in order to implement those customer requirements. For example, SCP 101 may be programmed such that all calls arriving for the particular 800 number be routed to a Los Angeles office on Monday and Tuesday, but to the New York office all other days. Alternatively, the SCP can be programmed to route calls to specific locations based upon the time of day, for example, or any other parameter. Thus, an incoming call to the 800 number causes telephone switches 102 or 103 to query the SCP, after which the SCP sends a message to the appropriate switch to effectuate call routing. The call may be routed to one of the telephones 105-110, or may be routed to one of the "other switches" indicated but not shown in FIG. 1. Moreover, different switches may be programmed to route the same 800 number to different places. Thus, callers on the east and west coasts can dial the same number, yet the east coast call will be routed to a New York office, while the west coast call will be routed to a Los Angeles office. In general, the SCP translates the logical number dialed by the caller, into the physical number, to which the call should be routed.
The SCP also provides other intelligent network services. For example, assume that SCP 101 is programmed to route the calls to one of telephones 105-110. In such a case, another function which must be included in SCP 101 is to keep track of how many of telephones 105-110 are available for incoming calls. Thus, each time SCP 101 routes a call, it updates an associated counter to reflect the fact that another one of the telephones 105-110 is in use and is thus unavailable to accept incoming calls. Each time one of the cells is disconnected via the service representative hanging up, the counter is also updated to reflect this fact. Since both switches 102 and 103 communicate in a similar manner to SCP 101, it is evident that SCP 101 should always be able to determine the total number telephones 105-110 which are available to accept incoming calls. If the SCP 101, in attempting to route a call to the corporate office 104, determines that all the telephones 105-110 are currently being used, than the appropriate one of switches 102-103 is instructed to queue that call until one of the telephones becomes available. The switches may be programmed to play a message while the call is awaiting service in the queue, so that rather than hearing a busy signal, the caller is informed that his call will be serviced shortly. In other arrangements, the call is routed to a PBX, located on the customer's premises, and the PBX either routes the call or queues it, depending upon whether or not there are any available telephone lines.
Two problems are inherent in the above described system. First, there is a finite time lag between the time that the SCP determines that there is an available telephone, and the time the switch routes the call to the corporate office. If there is only one or two available telephones, there is a substantial probability that they could both be taken off hook during this time lag; e.g. to make an outgoing call. If the switch then attempts to route an incoming call to one of these telephones, the customer will get a busy signal, an undesirable result in service oriented industries.
The second problem with the system described above is that, in addition to routing and queuing the toll free 800 calls, the switches 102-103 and telephones 105-110 are normally also used for regular telephone calls; i.e. caller billed calls. These calls arrive at the switches 102-103 at random times and are routed by the switches to other telephones or other switches, with no interaction by the SCP. Thus, while the SCP can count how many 800 calls arrive and are terminated, the counter in the SCP may not reflect the actual number of telephones 106-110 which are available, because some of these telephones may be occupied with telephone traffic that the SCP is unaware of. Consequently, the SCP may order calls queued when there are telephones available, and may order calls to be routed when there are no available telephones to route them to.
The problem remaining in the prior art is to provide IN services in a reliable and efficient manner to telecommunications customers who may also need to use regular network services.